In the original conventional technology of fasteners employed to securely attach one object to another, such as for example one part to another in the case of an automobile or an appliance, has utilized a nut on one of the two objects, usually welded or glued to the back of said object, and a bolt passing through a hole on the second object in a manner to be engaged by the nut, thereby securing the two objects together.
This arrangement presents many problems, among which, one of the most important is that in the case that one object is hollow, the nut has to be in place at the back of the hollow object before assembling the two objects together. If for any reason the nut is misplaced, and/or if it becomes desirable to introduce a new fastening connection between the two objects, the task of achieving such connection becomes very difficult if not impossible for all practical purposes.
The so-called "quick nuts" have also been used to connect two objects. In addition, vibration during the operation of a device, such as an automobile or appliance for example, containing the two objects results very often in loosening of the bolt or "quick nut" and in either full disassembling of the objects from each other, or in a vibration noise which is most annoying and often of unacceptable levels. Further, such connections are not water-resistant and water may be easily penetrate the connection point and be transferred from one side of one or both objects to the other side.
Recently, fasteners of the type described in U.S. Pat. No. 4,500,238 (Vassiliou) have been utilized to reduce considerably the potential of bolt or screw loosening and vibration. They have also eliminated the problem of having to place one member of the fastener at the back portion of the hollow object. These fasteners are placed through a slot from the front part of the hollow object. An expanding member, being usually a bolt or a screw, supports the second object by forcing the legs of the fastener (as described for example in U.S. Pat. No. 4,500,238) to open or expand, thereby securing the two objects together. The fasteners of this type have greatly improved the prevailing torque (as defined hereinbelow), as well as the pulling force (as also defined hereinbelow) of the system. The legs of the fastener are supported by a head having an upper side and a lower side joined by side bents.
In the fasteners of the above type, when an increasingly higher force is applied on the screw to pull it away from the fastener, there is reached a value of the force (pulling force) at which failure (separation of the expanding member from the fastener or breaking a part of the fastener) occurs. The failure usually occurs at the side bents which join the upper side of the head of the fastener with the lower side. This failure is quite abrupt as the head of the fastener splits all of a sudden.
One major object of the instant invention is to provide fasteners which are characterized by highly increased pulling force combined with more gradual failure, among other advantages.